Download MendeleyThe L3 loop and C-terminal phosphorylation jointly define Smad protein trimerization.
Chacko, B.M., Qin, B., Correia, J.J., Lam, S.S., de Caestecker, M.P., Lin, K.(2001) Nat Struct Biol 8: 248-253
- PubMed: 11224571
- DOI: https://doi.org/10.1038/84995
- Primary Citation of Related Structures:
1G88 - PubMed Abstract:
Smad proteins mediate the transforming growth factor beta responses. C-terminal phosphorylation of R-Smads leads to the recruitment of Smad4 and the formation of active signaling complexes. We investigated the mechanism of phosphorylation-induced Smad complex formation with an activating pseudo-phosphorylated Smad3. Pseudo-phosphorylated Smad3 has a greater propensity to homotrimerize, and recruits Smad4 to form a heterotrimer containing two Smad3 and one Smad4. The trimeric interaction is mediated through conserved interfaces to which tumorigenic mutations map. Furthermore, a conserved Arg residue within the L3 loop, located near the C-terminal phosphorylation sites of the neighboring subunit, is essential for trimerization. We propose that the phosphorylated C-terminal residues interact with the L3 loop of the neighboring subunit to stabilize the trimer interaction.
Organizational Affiliation:
Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 55 Lake Ave. North, Worcester, Massachusetts 01655, USA.
